Cumene hydroperoxide (CHP) is produced as an intermediate product in the manufacture of phenol from cumene and oxygen. In the BP Chemicals/Hercules and similar phenol processes, cumene is oxidized to CHP which can then be cleaved with sulfuric acid to yield phenol and acetone. These processes account for nearly all the phenol produced in the world today and are described in numerous patents and published literature dating back to the early 1950's. CHP synthesis yields small amounts of the following which are considered impurities: cumene, α-methylstyrene (AMS), dimethyl benzyl alcohol (DMBA) and acetophenone (AP). Further processing steps such as those described in U.S. Pat. No. 4,654,124, assigned to the same assignee as the present invention and incorporated in its entirety herein by reference, are necessary to remove these impurities and color formers from the CHP. Such purification as by the methods of the '124 patent may result in a CHP solution with a purity of greater than 92 weight percent.
Under United States federal regulations, 90 weight percent CHP is the maximum concentration permitted for domestic transport (49 C.F.R., Sec. 173.225, Organic Peroxide Table-revised Oct. 1, 1998). Therefore, refined CHP must be diluted, typically with cumene, to a concentration of 82 weight percent-90 weight percent to produce commercial grades of CHP that can be transported in compliance with these regulations.
The use of cumene as a diluent of CHP solutions presents several problems for CHP producers, transporters and end users. First, because the U.S. Clean Air Act Amendments (Public Law 101–549 Sect. 112(b)) classify the diluent, cumene, as a hazardous air pollutant, precautions must be taken when producing, transporting and using CHP solutions to minimize cumene emissions. Second, because cumene can be considered an impurity in CHP solutions, it may have to be removed by the end user, thereby creating additional hazardous emissions problems. Third, if the cumene added to CHP solutions is not removed, it can result in the end user's finished product containing unacceptable impurities. Fourth, the climatic conditions at the end user's facility may vary and necessitate changing the concentration of purified CHP utilized. A lower concentration CHP solution, i.e., higher cumene, typically is used to prevent the CHP solution from freezing in colder months, but a higher concentration CHP solution, i.e., lower cumene, is used in warmer months. Finally, the presence of cumene in CHP solutions may result in a reduced yield in the end user's process(es). The Inventors are unaware of any diluent, other than cumene, that is being used commercially with CHP.
Therefore, a need exists in the art for a CHP-diluent solution which will reduce or eliminate the hazardous emission problems associated with current CHP solutions, thus making CHP solutions more environmentally acceptable to produce, transport and use. In addition, the CHP-diluent solution should have minimal or no detrimental effects on the end user's finished product or process yield(s). The CHP-diluent solution should also preferably depress the CHP solution's freezing point to obviate the necessity of CHP users having to switch concentrations of CHP in response to changing climatic conditions at their facilities. Moreover, the diluent should have minimal effect on the viscosity of the resultant solution.